Aslam-O-Alaikum,
LNG got into my notice due to reference from a friend I had no idea there was something called LNG and was around since more then 50 year in the world, and according to him average of LNG is 400 KM with AC on his vehicle which is on CNG just 130 KM with AC on long
So got curios to research about it on internet because some safety concerns came into the mind by searching the work LNG stand for, and 3 time the average is justifiable as CNG is normally 200 to 250 times compressed then the pipe natural gas while LNG is 600 time more volume due to it liquid state that is obtained by freezing the gas
Checking out but I think so far it is not safe to use it in the existing CNG cylinder if you are not driving the vehicle much specially in this hot weather much more